I/O extender

[Luciano]

Hi,

See the Microchip MCP23016. (16-bit bidirectional I/O port expander).

You can address up to eight MCP23016 in your system so this
will give you up to 128 I/O pins.

Microchip MCP23016 16-Bit I2C™ I/O Expander
http://ww1.microchip.com/downloads/e...Doc/20090b.pdf

Interfacing The MCP23016 I/O Expander with the PIC16F877A:
http://ww1.microchip.com/downloads/e...tes/00245a.pdf


* * *

There is also a version with an 8-bit bidirectional I/O port.

Microchip MCP23008 8-Bit I/O Expander with I2C Interface
http://ww1.microchip.com/downloads/e...Doc/21919e.pdf

Best regards,

Luciano

[mychangl]

Thx Mackrackit.
It only High and Low I/O. i think shift register would be a good idea. 4 to 8 lines. Bringing total of 128 bit of I/O. Meaning total pin require is 7 ( 4 for address, Clock, Load and Serial Data ). Am i right ?

Thx Luciano for the suggestion. It really a new thing for me. But why both MCP23008 and MCP23016 have 3 addresses ? Can MCP23016 work with 16f84a ?

[Luciano]

Thx Luciano for the suggestion. It really a new thing for me.
But why both MCP23008 and MCP23016 have 3 addresses ?
Can MCP23016 work with 16f84a ?

Hi,

With three address lines you can set the address of up to eight devices.

Binary / Decimal 
============
000   =   0
001   =   1
010   =   2
011   =   3
100   =   4
101   =   5
110   =   6
111   =   7

The MCP23016 will work with the 16f84a.
Use the software I2C commands of PicBasic Pro. (I2CIN and I2COUT).

* * *

See also this: (Basic Stamp + MCP23016).
http://www.parallax.com/dl/docs/cols.../col/nv109.pdf

Best regards,

Luciano

[mychangl]

Use the software I2C commands of PicBasic Pro. (I2CIN and I2COUT).

Do you mean I2Read and I2Write ?
Sorry i am not familiar with it. However i would like to try.

Correct me if i am wrong.
From datasheet,
control 0h and 1h is to read or write to the ports
control 6h and 7h is to set port as input or output

Given scenario 1 :
Connect 23016 address as $01
Assign GP0.0 to GP0.7 as input (control address is 6h)
Assign GP1.0 to GP1.7 as output (control address is 7h)

the code will be :
addr var byte
addr=01
I2CWRITE DataPin,ClockPin,06,addr,[FF]
I2CWRITE DataPin,ClockPin,07,addr,[00]

Scenario 2 :
Read the data on GP0.0 to GP0.7 and put inside Sample1

the code will be :
I2CREAD DataPin,ClockPin,00,addr,[Sample1]

Scenario 3 :
Write data 44h on GP1.0 to GP1.7

the code will be :
I2CWRITE DataPin,ClockPin,00,addr,[44]

[Luciano]

Hi,

Yes, with PicBasic Pro use I2CREAD and I2CWRITE.
(I2CIN and I2COUT are for the PicBasic compiler).

Best regards,

Luciano

[mychangl]

I took longer time to try out with MCP23016 because i am still using shift register to expand the I/O. Last week i decided to try out MCP23016. However it doesn't work, after few days trial & error and change the address, i almost give up. Not sure what happen. either the code or the IC faulty because i only have one piece.

Can someone advice ?
Appreciate that.


'MASTER CODE
'This test is to check output functionality ( LED ) - Running LED
'MCP23016 connected to address 0

INCLUDE "modedefs.bas"


'*****PORT Setup********************************************* *****************
GreenLED VAR PORTA.0'O Indicator Green
SDA VAR PORTA.1 'O Serial Data
SCL VAR PORTA.2 'O Serial Clock
RedLED VAR PORTA.3 'O Indicator Red

'*****Constant************************************ ****************************
CtrlRW1 CON 00 'Access to Set1 GP0
CtrlRW2 CON 01 'Access to Set2 GP1
CtrlDir1 CON 06 'Access to Set1 IODIR/0
CtrlDir2 CON 07 'Access to Set2 IODIR/1


'**VARIABLES************************************** ****************************
Address VAR BYTE 'Address size
Set1 VAR BYTE 'Place to put Data Set1
Set2 VAR BYTE 'Place to put Data Set2

Address=0 'Select MCP23016 address as 0

Set1=0 'Clear Set1
Set2=0 'Clear Set2


'*****INITIALIZING MCP23016 All as Output**************************************
I2CWrite SDA,SCL,CtrlDir1,Address,[00] 'Set as Output
Pause 10 'Delay 10ms
I2CWrite SDA,SCL,CtrlDir2,Address,[00] 'Set as Output
Pause 10 'Delay 10ms


Start :
Set1=$FF 'To turn on all LEDs connected to Set1
Set2=$FF 'TO turn ON all LEDs connected TO Set2

I2CWrite SDA,SCL,CtrlRW1,Address,[Set1] 'Turn on the LEDs
Pause 10 'Wait 10ms

I2CWrite SDA,SCL,CtrlRW2,Address,[Set2] 'Turn on the LEDs
Pause 10 'Wait 10ms


GoTo Start

[keymuu]

......
'*****INITIALIZING MCP23016 All as Output**************************************
I2CWrite SDA,SCL,CtrlDir1,Address,[00] 'Set as Output
Pause 10 'Delay 10ms
I2CWrite SDA,SCL,CtrlDir2,Address,[00] 'Set as Output
Pause 10 'Delay 10ms


Start :
Set1=$FF 'To turn on all LEDs connected to Set1
Set2=$FF 'TO turn ON all LEDs connected TO Set2

I2CWrite SDA,SCL,CtrlRW1,Address,[Set1] 'Turn on the LEDs
Pause 10 'Wait 10ms

I2CWrite SDA,SCL,CtrlRW2,Address,[Set2] 'Turn on the LEDs
Pause 10 'Wait 10ms

GoTo Start

You could have a label after the line where to jump if an error occurs with I2C, like this:
I2CWrite SDA,SCL,CtrlRW1,Address,[Set1], errorLabel
...
errorLabel:
LCDOUT "Error....

[mackrackit]

Thx Mackrackit.
It only High and Low I/O. i think shift register would be a good idea. 4 to 8 lines. Bringing total of 128 bit of I/O. Meaning total pin require is 7 ( 4 for address, Clock, Load and Serial Data ). Am i right ?

Thx Luciano for the suggestion. It really a new thing for me. But why both MCP23008 and MCP23016 have 3 addresses ? Can MCP23016 work with 16f84a ?

If you go with shift registers you will need a clock/load set for inputs and one for outputs.
Look at a HC595 for output and HC165 for inputs (I think, been awhile)

The solution that Luciano gave looks nice. I did not know about these chips. Learned something new and it is the fisrt day of the year Off to a good start.

[mister_e]

Those microchip I/O extender are really nice. In the past i also used PCF8574A, maybe easier to find it locally 'cause it's a very old one.. still popular i guess.

[ronjodu]

I use 3 of the Maxim Max6957's for a total of 60 additional I/O's with only 3 PIC pins thru SPI interface. They also have a I2C version. In my app. 52 are used for LED's and 8 will be used for relays. TFM is a bit intimidating at first. I could post some code if interested.

Hope this helps.

!!!!!!!!!!!! Happy New Year to All !!!!!!!!!!!!!!

[mychangl]

Interesting. If it is feasible, why not. However I just checked with our local distributor and they do not have max6957. Perhaps i should keep looking for the availability. I keep that in mind. Thx Ronjodu